Fen Management Handbook - Scottish Natural Heritage

10.3.3 Vegetation Mapping
An initial identification of the plant communities present in a fen, with approximate
mapping of the community boundaries, is crucial for identification of key species
and informing the understanding of physical mechanisms affecting a site. This is
usually based on a survey using the NVC methodology (Rodwell J. S. ed. 1991 –
2000).
The NVC methodology is both rigorous (i.e. careful application of the method will
yield consistent and reliable results) and robust (i.e. it is not sensitive to minor
differences in technique). However, it is a plant community classification method,
not a mapping or monitoring method. The recording method is based on selecting
locations for quadrats that appear typical of the community that is being observed,
well within the boundaries of that apparent community.
A set of NVC quadrats can provide an almost complete species list for a defined
area, which can be quickly completed by a check for other species outside the
quadrats, using the DAFOR abundance scale. This can provide the basis for the
qualitative monitoring of the community in that part of the site.
Basic fen monitoring techniques
Quadrats are square frames (usually 4 square metre (2x2m) on fens)
used to sample vegetation. The presence of plant and moss species and
their relative density or abundance is recorded within the quadrat. The
location of the quadrat is described with a GPS, or marked with a post,
so that the vegetation can be re-surveyed and described repeatedly at
the same location in future to detect changes. Further information on
quadrat methodology can be found in Ecological Census Techniques
(Sutherland, 2006).
Transects, or lines, are used to sample vegetation along a gradient
or gradual change of the vegetation. The transect can be up to 100
m long or more, the length depending on the changes or gradient to
be monitored. Vegetation is normally sampled with a quadrat at fixed
intervals, say every 5 m, along the transect, or where tall vegetation (such
as reed encroachment) or abiotic changes (such as change in slope,
groundwater seepage zone) occur. The environment is also normally
measured along the same transect so that changes in vegetation can be
correlated to changes in the environment, and vice-versa.
Advantages of vegetation community mapping and survey include:
– The NVC methodology can provide a clear and rigorous description of the plant
communities present on the site.
– A set of well recorded NVC quadrats can provide useful species presence and
abundance data for a defined location.
– Where well-defined, boundaries between communities can be accurately mapped
using appropriate techniques.
– Two sets of data are generated; geographical data for the community extent and
qualitative data for the community composition in a particular area of the site.
– The data can be presented graphically, as readily comprehensible maps.
– GIS mapping gives precise measurement of areas, allowing changes to be quantified.
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